Water Hyacinth’s Effect on Greenhouse Gas Fluxes: A Field Study in a Wide Variety of Tropical Water Bodies

Abstract

Water hyacinth beds tend to be net GHG sinks; A low water hyacinth cover offsets open water emissions due to carbon uptake; Depth and plant biomass explain a large share of the variation in GHG fluxes.

Short-term effects of macrophyte removal on emission of CO2 and CH4 in shallow lakes

“…At Hartbeespoort Dam, P. crassipes stands showed very high daytime CO 2 emission rates of 100-300 mg C m − 2 h − 1 before removal. Our findings contrast with previous studies that have found that P. crassipes can often offset CO 2 emissions in freshwater systems (Oliveira Junior et al, 2021;Peixoto et al, 2016), due to its high primary production under nutrient-rich conditions (Junk and Howard-Williams, 1984). A previous study in the Amazon and Pantanal has reported very high daytime CO 2 uptake rates of − 1000 ± 500 mg C m − 2 h − 1 , which compensated for night-time emissions, resulting in a net CO 2 sink (Oliveira Junior et al, 2021).…”

“…Our findings contrast with previous studies that have found that P. crassipes can often offset CO 2 emissions in freshwater systems (Oliveira Junior et al, 2021;Peixoto et al, 2016), due to its high primary production under nutrient-rich conditions (Junk and Howard-Williams, 1984). A previous study in the Amazon and Pantanal has reported very high daytime CO 2 uptake rates of − 1000 ± 500 mg C m − 2 h − 1 , which compensated for night-time emissions, resulting in a net CO 2 sink (Oliveira Junior et al, 2021). The contrasting findings in our study could result from using opaque chambers, as we exclude the direct uptake of CO 2 from the atmosphere by P. crassipes.…”

“…Total CH 4 fluxes, however, showed a threefold increase when P. crassipes was removed. As P. crassipes did not root in the sediment at our study sites (Oliveira Junior et al, 2021), we assume plant-mediated methane transport did not play a substantial role and that the total flux is made up of diffusive fluxes and ebullition (Fig. 6).…”

Carbon fluxes in subtropical shallow lakes: contrasting regimes differ in CH4 emissions

“…This indicates that the littoral area can play an important role contributing to the overall emission of the lake. Although the actual importance of the littoral zone may deviate from our estimations as we did not include plant-mediated CH 4 fluxes of floating and emergent plants-which can be considerable (Bansal et al, 2020;Oliveira Junior et al, 2020)-nor the CO 2 uptake by these plants, it does point out that the littoral area needs more attention in further studies.…”

Worms and submersed macrophytes reduce methane release and increase nutrient removal in organic sediments

“…The aerenchyma of emergent macrophytes connects the sediment to the atmosphere and may favor CH 4 evasion. Methane greenhouse net effect can be offset by plants CO 2 fixation rates (Van Der Nat and Middelburg 1998;Laanbroek 2010;Oliveira-Junior et al 2020). ROL by submersed macrophytes might inhibit methanogenesis or favor aerobic CH 4 oxidation, reducing net emissions (Ribaudo et al 2011;Kosten et al 2016).…”